the process when students

construct meaning students construct meaning from the most basic units of language, including letters, letter clusters, and words.

 the use of background knowledge to predict the meaning of the reading or listening text, for example, readers develop hypotheses about the content of a text

This type of reading involves the deconstruction of a text. The aim is to get as much information as possible, we are concerned with every detail related to the text. 

This type of reading refers to simply reading as much as possible, without concerning oneself with every detail. Occasional unknown words are not supposed to get too much attention because focus is on the overall meaning